The whole deal with Samsungs update was to make options that are usually high up on the screen more easily accessible since the phones are becoming so exceptionally tall. Having a padding at the top makes it easier for you to scroll further up on the page, thereby making things that were previously an uncomfortable reach because they were so high on the screen, now easily accessible without stretching your finger way up to the top of your giant screen.
You'll notice the same is the case with all other stock Samsung apps, including the phone Settings. In theory it's a good idea, but execution does seem a bit poor. The Samsung dialer however, brought options such as 'recents' 'keypad' 'contacts' etc., to the very bottom of the screen, as did the Gallery, both huge improvement in my opinion.
With this being said, it would be nice if that were an optional setting. I would recommend a third party app, with this reason hardly being high on the list of 'why', but still just another reason.
I use Textra, absolutely fantastic. I would opt for Google's Messages over Samsung too. But Textra is easily tops in my book. Highly recommend checking it out. I think the only reason to stick with the stock app is if you're super picky about having all your apps and services looking very uniform to each other.